using System;
using System.Runtime.InteropServices;
using System.Text;

namespace DotGecko.Gecko.Interop
{
	[ComImport, Guid("53f0ad17-ec62-46a1-adbc-efccc06babcd"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
	public interface nsIHandlerService //: nsISupports
	{
		/**
		 * Retrieve a list of all handlers in the datastore.  This list is not
		 * guaranteed to be in any particular order, and callers should not assume
		 * it will remain in the same order in the future.
		 *
		 * @returns a list of all handlers in the datastore
		 */
		nsISimpleEnumerator Enumerate();

		/**
		 * Fill a handler info object with information from the datastore.
		 *
		 * Note: because of the way the external helper app service currently mixes
		 * OS and user handler info in the same handler info object, this method
		 * takes an existing handler info object (probably retrieved from the OS)
		 * and "fills it in" with information from the datastore, overriding any
		 * existing properties on the object with properties from the datastore.
		 *
		 * Ultimately, however, we're going to separate OS and user handler info
		 * into separate objects, at which point this method should be renamed to
		 * something like "get" or "retrieve", take a class and type (or perhaps
		 * a type whose class can be determined by querying the type, for example
		 * an nsIContentType which is also an nsIMIMEType or an nsIProtocolScheme),
		 * and return a handler info object representing only the user info.
		 *
		 * Note: if you specify an override type, then the service will fill in
		 * the handler info object with information about that type instead of
		 * the type specified by the object's nsIHandlerInfo::type attribute.
		 *
		 * This is useful when you are trying to retrieve information about a MIME
		 * type that doesn't exist in the datastore, but you have a file extension
		 * for that type, and nsIHandlerService::getTypeFromExtension returns another
		 * MIME type that does exist in the datastore and can handle that extension.
		 *
		 * For example, the user clicks on a link, and the content has a MIME type
		 * that isn't in the datastore, but the link has a file extension, and that
		 * extension is associated with another MIME type in the datastore (perhaps
		 * an unofficial MIME type preceded an official one, like with image/x-png
		 * and image/png).
		 *
		 * In that situation, you can call this method to fill in the handler info
		 * object with information about that other type by passing the other type
		 * as the aOverrideType parameter.
		 *
		 * @param aHandlerInfo   the handler info object
		 * @param aOverrideType  a type to use instead of aHandlerInfo::type
		 *
		 * Note: if there is no information in the datastore about this type,
		 * this method throws NS_ERROR_NOT_AVAILABLE. Callers are encouraged to
		 * check exists() before calling fillHandlerInfo(), to prevent spamming the
		 * console with XPCOM exception errors.
		 */
		void FillHandlerInfo(nsIHandlerInfo aHandlerInfo, [In, MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(ACStringMarshaler))] String aOverrideType);

		/**
		 * Save the preferred action, preferred handler, possible handlers, and
		 * always ask properties of the given handler info object to the datastore.
		 * Updates an existing record or creates a new one if necessary.
		 *
		 * Note: if preferred action is undefined or invalid, then we assume
		 * the default value nsIHandlerInfo::useHelperApp.
		 *
		 * @param aHandlerInfo  the handler info object
		 */
		void Store(nsIHandlerInfo aHandlerInfo);

		/**
		 * Whether or not a record for the given handler info object exists
		 * in the datastore. If the datastore is corrupt (or some other error
		 * is caught in the implementation), false will be returned.
		 *
		 * @param aHandlerInfo  a handler info object
		 *
		 * @returns whether or not a record exists
		 */
		Boolean Exists(nsIHandlerInfo aHandlerInfo);

		/**
		 * Remove the given handler info object from the datastore.  Deletes all
		 * records associated with the object, including the preferred handler, info,
		 * and type records plus the entry in the list of types, if they exist.
		 * Otherwise, it does nothing and does not return an error.
		 *
		 * @param aHandlerInfo  the handler info object
		 */
		void Remove(nsIHandlerInfo aHandlerInfo);

		/**
		 * Get the MIME type mapped to the given file extension in the datastore.
		 *
		 * XXX If we ever support extension -> protocol scheme mappings, then this
		 * method should work for those as well.
		 *
		 * Note: in general, you should use nsIMIMEService::getTypeFromExtension
		 * to get a MIME type from a file extension, as that method checks a variety
		 * of other sources besides just the datastore.  Use this only when you want
		 * to specifically get only the mapping available in the datastore.
		 *
		 * @param aFileExtension  the file extension
		 *
		 * @returns the MIME type, if any; otherwise returns an empty string ("").
		 */
		void GetTypeFromExtension([In, MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(ACStringMarshaler))] String aFileExtension,
									  [In, Out, MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(ACStringMarshaler))] StringBuilder retval);
	}
}
